The present invention relates to magnetic head and magnetic recording and reproducing apparatus, and more particularly to ultra-high sensitivity reproducing magnetic head and magnetic recording and reproducing apparatus using superconducting quantum interference.
Advancement in high density magnetic recording is remarkable, and study on perpendicular magnetic recording suitable to high density magnetic recording is under progress. Further, in conventional longitudinal magnetic recording, high density recording is in progress due to improvement of magnetic head and recording medium.
Where linear recording density and track density are increased, a related area of the recording medium per bit or per wavelength decreases and a reproduced output decreases. Thus, if perpendicular magnetic recording is used, a signal having a linear recording density of up to 500 KBPI can be recorded. However, when the recorded signal is reproduced by a conventional magnetic head, an output is very low compared to a low recording density because a magnetic flux generated by magnetization of the signal of the medium is small. (See Papers of Lecture of Tenth Japan Applied Magnetic Institute, (1986) p. 335)